1. Field of the Invention
The invention proceeds from a high-voltage installation in accordance with the preamble of claim 1.
2. Discussion of Background
High-voltage installations are known which have a grounded metallic enclosure which is filled with an insulating gas, for example SF.sub.6, and whose internal surface situated opposite the high-voltage-carrying active parts is provided with a protective coating. This protective coating is to render this surface smooth, inter alia so that it can be cleaned without fibers or other residues of cleaning agents being retained by surface roughnesses of the internal surface, as a result of which the dielectric strength of the insulating-gas gap would be reduced. The surface of the active parts in such installations is often provided with a similar protective layer.
The publication DE 41 20 309 Al discloses a high-voltage installation which has a metallic enclosure which is filled with insulating gas and surrounds the voltage-carrying active parts. Provided on the internal surface of the enclosure as well as on the external surface of the active parts is a protective coating. In the case of this high-voltage installation, a reduction in the dielectric strength of the insulating-gas gap as a result of freely moving or fixed particles can occur only to a limited extent since the protective coatings are specially formed and are at least partly coated with a second protective coating. In such a high-voltage installation, electrically conductive particles do not as a rule move. Furthermore, the intensity of partial discharges caused by particles is markedly reduced in comparison with uncoated surfaces as a result of said coating. Free electrons, however, are not as a rule reliably rendered harmless in this type of high-voltage installation. The dielectric strength of the insulating-gas gap could, however, be improved if electrons which are produced in the vicinity of surfaces as a result of partial discharges at peaks or particles were captured. In addition, the application of a second protective coating is comparatively expensive.